add fibonacci implementations to integration tests

Signed-off-by: xermicus <cyrill@parity.io>

crates/integration/contracts/Fibonacci.sol

@@ -0,0 +1,62 @@
+// Source:
+// https://medium.com/coinmonks/fibonacci-in-solidity-8477d907e22a
+
+contract FibonacciRecursive {
+    function f(uint n) internal pure returns (uint) {
+        if (n <= 1) {
+            return n;
+        } else {
+            return f(n - 1) + f(n - 2);
+        }
+    }
+
+    function fib3(uint n) public pure returns (uint) {
+        return f(n);
+    }
+}
+
+contract FibonacciIterative {
+    function fib3(uint n) external pure returns (uint b) {
+        if (n == 0) {
+            return 0;
+        }
+        uint a = 1;
+        b = 1;
+        for (uint i = 2; i < n; i++) {
+            uint c = a + b;
+            a = b;
+            b = c;
+        }
+        return b;
+    }
+}
+
+contract FibonacciBinet {
+    function fib3(uint n) external pure returns (uint a) {
+        if (n == 0) {
+            return 0;
+        }
+        uint h = n / 2;
+        uint mask = 1;
+        // find highest set bit in n
+        while (mask <= h) {
+            mask <<= 1;
+        }
+        mask >>= 1;
+        a = 1;
+        uint b = 1;
+        uint c;
+        while (mask > 0) {
+            c = a * a + b * b;
+            if (n & mask > 0) {
+                b = b * (b + 2 * a);
+                a = c;
+            } else {
+                a = a * (2 * b - a);
+                b = c;
+            }
+            mask >>= 1;
+        }
+        return a;
+    }
+}

crates/integration/contracts/flipper.sol

@@ -4,7 +4,7 @@ pragma solidity ^0.8.24;
 contract Flipper {
     bool coin;
 
-    function flip() public payable {
+    function flip() public {
         coin = !coin;
     }
 }

crates/integration/src/lib.rs

@@ -32,6 +32,33 @@ mod tests {
 
     use crate::mock_runtime::{self, State};
 
+    #[test]
+    fn fibonacci() {
+        sol!(
+            #[derive(Debug, PartialEq, Eq)]
+            contract Fibonacci {
+                function fib3(uint n) public pure returns (uint);
+            }
+        );
+
+        for contract in ["FibonacciIterative", "FibonacciRecursive", "FibonacciBinet"] {
+            let code = crate::compile_blob(contract, include_str!("../contracts/Fibonacci.sol"));
+
+            let parameter = U256::from(6);
+            let input = Fibonacci::fib3Call::new((parameter,)).abi_encode();
+
+            let state = State::new(input);
+            let (instance, export) = mock_runtime::prepare(&code, None);
+            let state = crate::mock_runtime::call(state, &instance, export);
+
+            assert_eq!(state.output.flags, 0);
+
+            let received = U256::from_be_bytes::<32>(state.output.data.try_into().unwrap());
+            let expected = U256::from(8);
+            assert_eq!(received, expected);
+        }
+    }
+
     #[test]
     fn flipper() {
         let code = crate::compile_blob("Flipper", include_str!("../contracts/flipper.sol"));
@@ -75,7 +102,7 @@ mod tests {
         hasher.update(param);
         let expected = hasher.finalize();
         let received = FixedBytes::<32>::from_slice(&state.output.data);
-        assert_eq!(expected, received);
+        assert_eq!(received, expected);
     }
 
     #[test]